Various designs for hatch covers for railway cars have been available for some time. For example, U.S. Pat. No. 3,250,233 elongated hatch covers are disclosed in which a strap is mounted on one side of the opening and the strap is affixed to the cover by means of welding and/or bolts and latch means is provided at the opposite side of the opening for holding the strap down and the hatch cover closed during transit. A torsion bar is utilized to aid in raising the hatch cover to the open position.
While most hatch covers have been made of metal, recently the use of non-metallic material, particularly fiber reinforced plastic, or fiberglass for hatch covers has been suggested in U.S. Pat. No. 3,605,639. Longitudinal reinforcements are provided in accordance with this design.
It has also been suggested to provide a smaller hatch cover within a larger elongated hatch cover in U.S. Pat. No. 3,523,506. The large elongated opening may be used for loading ladings wherein dusting is not a problem. If dusting is a problem the smaller hatch opening may be used. Furthermore, in order to utilize the small cover it is necessary to unlatch both the large cover latch and the small cover latch. This operation is somewhat time consuming and can be unpleasant in inclement weather.